Abstract—In the first part of our work, we present the results of a comparative analysis of photometric observations of stars using the Kepler mission and its continuation K2. The comparability of the data was estimated by an indirect method based on the values of the stellar surface spottedness parameter \(S\) calculated by us, which were determined by the amplitudes of the brightness variability

Abstract—We present a database created within the project on studying edge-on galaxies. These galaxies provide a unique opportunity to study the three-dimensional distribution of the matter in galaxy disks, which is extremely important for analyzing the influence of internal and external factors on the evolution of galaxies. For the moment, extensive observed material has been accumulated on the kinematics

Abstract A three-component Stäckel model of the Galaxy, including the bulge, disk, and halo, is constructed. Parameter estimates of the potential are obtained as a result of fitting the model rotation curve to azimuthal velocities found from data on trigonometric parallaxes and spatial velocities of masers. The fitting method takes into account the measurement and natural dispersions of azimuthal velocities

Abstract—We propose a method of searching for radio sources exhibiting the Sunyaev–Zeldovich effect in the multi-frequency emission maps from the Planck mission data using a convolutional neural network. A catalog for recognizing radio sources is compiled using the GLESP pixelation scheme at the frequencies of 100, 143, 217, 353, and 545 GHz. The quality of the proposed approach is evaluated and the

Abstract—We briefly present the history of technical solutions aimed at improving the efficiency of spectroscopy on small- and moderate-diameter telescopes. We assess the current state of spectroscopy techniques and some of the perspectives.

Abstract We use the data of modern digital sky surveys (PanSTARRS-1, SDSS) combined with H I-line and far ultraviolet (GALEX) surveys to reclassify 165 early-type galaxies from the Catalog of Isolated Galaxies (KIG). As a result, the number of E- and S0-type galaxies reduced to 91. Our search for companions of early-type KIG galaxies revealed 90 companions around 45 host galaxies with line-of-sight

Abstract—The spectral properties of the inhomogeneities of the microwave background on Planck multi-frequency maps that are distant from the sources of the RCR catalog by the half-width of the power beam pattern of the high-frequency Planck complex (\( \pm 2'.5\)), as well as the spectral features of the sources depending on the presence of positive spots near them, are studied. About 830 objects of

Abstract—The paper presents the results of magnetic field measurements of 27 chemically peculiar stars in subgroups (c) and (d) of the Orion OB1 association. In total, more than 140 circularly polarized spectra were obtained and measured in the period from 2013 to 2020. An analysis of the results showed that 13 out of 24 CP stars in subgroup (c) have a magnetic field. At the same time, no field of

Absctract—The present study continues the investigation of the super-fast variability of line profiles in the spectra of stars of early spectral types. We studied the line-profile variability in the spectrum of the binary (O9.7Ib+B0III) star \(\zeta \) Ori A using the MSS spectrograph of the 6-m BTA telescope based on observations carried out on February 19, 2019. Short-period regular variations of

We use experimental data of the FIRST survey to construct the radiation pattern of external components of extended radio sources. The radiation pattern differs from spherical. The greatest deviation from sphere is observed in the region facing the central component, where there is a deep minimum. The minimum of radiation in the beam pattern is associated with the region where the regular magnetic field

We performed the comparative analysis of the properties of Ap and Am stars. It is shown that the main differences in the formation and evolution of these objects are due to the influence of a magnetic field in Ap stars.

The paper presents magnetic field measurements for 15 chemically peculiar (CP) stars of subgroup 1b in the Orion OB1 association. We have found that the proportion of stars with strong magnetic fields among these 15 CP stars is almost twice as large as in subgroup 1a. Along with this, the age of subgroup 1b is estimated as 2 Myr, and the age of subgroup 1a is in the order of 10 Myr. The average root-mean-square

Orbits of 20 visual double stars discovered by P. Couteau are computed for the first time. The observations for four of these stars, COU 384, COU 1067, COU 1681, and COU 2388, span arcs greater than or approximately equal to 180 degrees. Since the time of their discovery the stars, COU 384 and COU 2388 have already completed one revolution. COU 338, COU 567, COU 1003, COU 1607, and COU2086 have many

In this work, the orbital elements are improved and the total masses of the three close visual binary systems CVBSs: HIP 11352, HIP 70973, and HIP 72479 are precisely calculated. The calculations were performed based on an assessment of the latest Gaia DR2 and Hipparcos trigonometric parallax measurements. The morphology and kinematics of orbits are fitted to the observational data available in the

We estimated a number of parameters for small groups of stars in the open Pleiades star cluster using Gaia DR2 coordinate and proper motion data for stars in the region of radius d = 2.5° relative to the center of the cluster on the celestial sphere. We selected 36 wide pairs of stars with magnitudes mG < 15m and velocities of the stars in these pairs with respect to their geometric centers close to

We present the “StoP” photometer-polarimeter (Stokes-polarimeter) used for observations with the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences since the beginning of 2020. We describe the instrument and its parameters in observations performed in the photometric and polarimetric modes. We demonstrate the capabilities of the instrument through the polarimetry

Ultraluminous X-ray sources (ULXs) were identified as a separate class of objects in 2000 based on data from the Chandra X-Ray Observatory. These are unique objects: their X-ray luminosities exceed the Eddington limit for a typical stellar-mass black hole. For a long time, the nature of ULXs remained unclear. However, the gradual accumulation of data, new results of X-ray and optical spectroscopy,

An Erratum to this paper has been published: https://doi.org/10.1134/S1990341320040057

Abstract—We present the results of observations of radial velocity variability in stars with exoplanets. Observations of a number of stars with characteristic stellar magnitudes from 8.54m to 10.5m were carried out using a new high-resolution (R = 35 000–120 000) fiber-fed spectrograph mounted at the foundation of the 6-m BTA telescope, in the mode of resolutions from R = 45 000 to R = 65 000 with

Abstract—We present the measurements of masses of two exoplanets and one exoplanet candidate: the candidate we earlier confirmed in the KOI-974 system, a new TESS candidate in the TOI-1797 system, and the well-known hot Jupiter MASCARA-3b. The observations were carried out using the first prototype of the high-resolution fiber-opticspectrograph of the 6-m BTA telescope, and with the BOES spectrograph

Abstract—In this work a search was carried out for globular clusters belonging to the Sagittarius (Sgr) tidal stream using the analysis of spatial positions, radial velocities relative to the Galactic Standard of Rest (VGSR), proper motions and ratio of “age–metallicity” ([Fe/H]) for globular clusters and for stars in the tidal stream. As a result, three categories of globular clusters were obtained:

Abstract—We briefly discuss the stages of the development of high-resolution spectroscopy methods used with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, which are related to the problem considered. We consider the possibility of the multiple increase of the stellar spectroscopy efficiency as a result of application of state-of-the-art solutions in the

Abstract—The features of the simplest inner structures of a magnetic field, the central dipole and the shifted dipole, are considered. Their secular stability, solidity of rotation, and a great variety of orientations of magnetic dipoles and magnitudes of magnetic fields are noted.

Abstract—The paper describes Zeiss-1000, the one meter telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS), the history of the development of its observation methods and potential areas of astrophysical research. Detailed attention is paid to instruments and methods of observation which are in service nowadays.

Abstract—We investigate statistical patterns in the distribution of the orbits of long-period comets that belong to the inner region of the Oort cloud (with aphelion distances, Q, lying in the 50–2000 AU interval). We show that the distribution of aphelia is not random and such patterns can be due, in particular, to the presence of hypothetical massive bodies in the region considered. We varied the

Abstract—Several parameters of the Pleiades cluster were estimated. We used Gaia DR2 data on the coordinates, proper motions, and radial velocities of stars in regions with radius d° =2.5° and size 60° × 60° around the cluster center. Based on data on stars with magnitudes mG ≤ 18m, we constructed a map and profile of the density, luminosity and mass functions of the cluster, determined the cluster

Abstract—Based on the SDSS catalog data the properties of galaxies with quenched star formation (QGs) within the “splashback”-radius of galaxy clusters Rsp and beyond it have been studied. We used a sample of 40 groups and galaxy clusters and a sample of field galaxies at 0.02 < z < 0.045. The radii Rsp were defined from the observed integral distribution of the number of galaxies as a function of

Abstract—According to the exact positions and proper motions of the three components of the star ADS48 from Gaia DR2, their parallax and radial velocities for the epoch 2015.5 the instantaneous relative positions and motions of the components were determined. Only from the Gaia DR2 observations, the family of orbits of the AB pair was calculated by the method of apparent motion parameters, from which

Abstract—The nearby dwarf galaxy NGC 3077 is known for its peculiar morphology, which includes numerous dust lanes and emission-line regions. The interstellar medium in this galaxy is subject to several perturbing factors. These are primarily the central starburst and tidal structures in the M81 group. We present a comprehensive study of the state of ionization, kinematics, and chemical composition

Abstract—Based on the archival images from the Hubble Space Telescope, we performed the photometry of the brightest galaxies of the Dorado group: NGC 1433, NGC 1533, NGC 1566, and NGC 1672. In the obtained CM-diagrams, red giants are specified, and distances to galaxies are measured by the TRGB method. The estimates obtained: 14.2 ± 1.2, 15.1 ± 0.9, 14.9 ± 1.0, and 15.9 ± 0.9 Mpc show that all the

Abstract—The paper provides a review of important results of studies of chemically peculiar and related magnetic stars. More than 90 papers published in the world leading astronomical journals mainly in 2019 were analyzed. The most important results: high-accuracy photometric light curves were obtained during the TESS satellite; we discovered several dozen of new chemically peculiar magnetic stars;

Abstract We present results of the study of the large scale distribution of galaxies up to z ~ 0.8 in the field HS 47.5–22 based on the photometric data obtained with the 1 m Schmidt telescope of the Byurakan astrophysical observatory (BAO NAS). The complete sample includes 28 398 galaxies brighter than \({{m}_{{{\text{AB}}}}} = {{23}^{{\text{m}}}}~\)up to \(z \sim 0.8\). Clusterings of density in

Abstract—We analyze the spatial and kinematic properties of a large sample of young T Tauri type stars in a 500 pc radius solar neighborhood, closely related to the Gould belt. The following parameters of the exponential density distribution have been determined: the average \({{({{z}_{{\text{G}}}})}_{ \odot }} = - 25 \pm 5\) pc and scale height \({{h}_{{\text{G}}}} = 56 \pm 6\) pc. We propose a method

Abstract—The paper presents complete results of measurements of the magnetic-field longitudinal component Be and radial velocities VR for 163 objects, mainly main-sequence chemically peculiar stars and standards. Observations were carried out in 2012 at the 6-m BTA telescope using the Main Stellar Spectrograph (MSS) equipped with a Zeeman analyzer. Six new chemically peculiar magnetic stars were discovered:

Abstract—This study continues the investigation of the super-fast variability of line profiles in the spectra of stars of early spectral classes performed in 2017 and 2018. We investigated the variability of line profiles in the spectra of OBA stars with the SCORPIO multi-mode focal reducer at the 6-m SAO RAS telescope (BTA). Short-period regular variations of the H and He lines were detected in the

Abstract—This paper presents a method for searching for polar candidates using mid-band filters. One of the spectral features of polars is the HeII λ4686 strong emission line. We selected the Edmund Optics color filters with central wavelengths of 470, 540, and 656 nm and a transmission bandwidth of 10 nm. These filters cover the regions of the HeII λ4686 line, continuum, and the Hα line respectively

Abstract We present the results of determination of the age, helium mass fraction (Y), metallicity ([Fe/H]), and abundances of the elements C, O, Na, Mg, Ca, Ti, Cr and Mn for 26 globular clusters of the Galaxy. In this work, we apply a method developed by us that employs medium-resolution integrated-light spectra of globular clusters and models of stellar atmospheres and it is supplemented in this

Abstract—The star-forming regions (SFRs) in the peculiar galaxies NGC 660, NGC 1512, NGC 4395 and NGC 4618 are studied. The relationships between such characteristics of star forming regions as UV, near- and far-IR fluxes, as well as in the Hα and HI lines, surface brightness in these ranges, and the scatter of the radial velocities of ionized and neutral hydrogen are considered. It is shown that in

Abstract—This work is a continuation of the studies of the ultrafast variability of line profiles in the spectra of early-type stars. Line profile variations in the spectrum a chemically peculiar A0Vp star α2 CVn are investigated using the January 6, 2020 observations carried out with the 6-meter BTA telescope at SAO RAS equipped with the MSS spectrograph. Regular short-term periodic variations of

Abstract—The article presents the results of multicolor photometry, medium and low resolution spectroscopy of the red nova V838 Mon remnant for 16 years after the 2002 outburst. We also used the archival photometry with the photographic plates of the Sonneberg and Moscow collections from 1928 to 1994. Analysis of these observational data confirmed that the progenitor of the V838 Mon explosion was a

Abstract—Modern Multimessenger Astronomy is a powerful instrument for performing crucial tests of the Standard Cosmological Model in the wide redshift interval up to z ∼ 10. This testing is principally important for discussion related to discrepancies between local and global measurements of cosmological parameters. We present a review of multimessenger gamma-ray burst observations currently performed

Abstract We provide an analytical description of the method for the determination of the coordinates of solar radio sources from multi-azimuth observations on RATAN-600. We analyze models of the displacement of the object across the scan depending as a function of azimuth taking into account solar rotation and suggest a method for estimating the rate of displacement due to rotation. We demonstrate

Abstract We use the data of our extended catalog of spectroscopic determinations of elemental abundances in the atmospheres of Galactic-field RR Lyrae type variables to show that metal-rich RR Lyraes ([Fe/H] > −1.0) have anomalous abundances of some elements. In particular, the relative abundances of scandium, titanium, and yttrium in metal-rich RR Lyrae type variables are lower than the corresponding

Abstract—Using the data from the second release of the Gaia exoatmospheric astrometric observatory archive the structure of the Cas5 OB association and the parameters of stars of extremely high luminosity that it contains have been refined. Two groups of OB stars have been isolated in the direction of the association at distances 3.3 and 4.3 kpc.

Abstract—The variability of radial velocities, equivalent widths and central line depths in the spectrum of the κ Cas supergiant was studied using CCD coude-echelle spectra with high spectral resolution and signal-to-noise ratio. The radial velocity variability of all the studied lines is due to non-radial pulsations. The variability parameters (period P, amplitude A and average value γ) of radial

AbstractMillimeter- and submillimeter-wave maps are used to select potential candidate objects with the Sunyaev–Zeldovich effect in the vicinity of RCR (RATAN Cold Refined) radio sources. The properties of “hot” and “cold” spots in the right-ascension interval 2h ≤ RA ≤ 17h and the declination strip \({\text{De}}{{{\text{c}}}_{{2000}}} = 45^\circ .9' \pm 15'\) are studied. In the entire strip a total

Abstract—Observations of facular areas of the Sun using the Helioseismic and Magnetic Imager device of the Solar Dynamics Observatory allow detecting long-period oscillations in the magnetic field of facular knots with periods ranging from 30 to 250 minutes. Statistically significant oscillation modes are selected by the method of time series decomposition in empirical modes. During the observation

Abstract—In the paper the possibility of the presence of a non-thermal component described by a power law spectrum in the X-ray spectra of OB stars is investigated. The low-resolution spectra of 101 OB stars obtained using the EPIC camera on the XMM satellite are analyzed. It is concluded that the contribution of the non-thermal component of X-ray emission can be significant and even determining for

Abstract—We critically review the results of earlier studies on magnetic stars with anomalous helium lines. We discuss the issues associated with the fossil-field theory and the scenario of the formation of magnetic stars. A special feature of the results of our study is that they are derived from more than 160 direct estimates of average surface magnetic fields Bs or models obtained by the method

Abstract—The paper analyzes the origin for the separation of gas-and-dust disks around young stars into two large groups: those with circular and spiral structures. Such a separation of disk structures is explained by the existence of stable and unstable gas-dynamic equilibrium of protostellar envelopes. A model of wave disturbances of the gas-dust protostellar envelopes is constructed. The equation

AbstractEnceladus is an attractive place to look for signs of life thanks to liquid water and the availability of energy. Recent research has proven that the ejected material of Enceladus south pole consists of water vapor, water ice, carbon dioxide, methane and molecular hydrogen. Possible similarities of physical and chemical conditions between Enceladus ocean bottom and the carbonate mineral matrix

Abstract—Based on archived images from the Hubble Space Telescope, stellar photometry of the dwarf galaxy Coma P, located near the Virgo galaxy cluster, was performed. The selection of weakly luminous regions of the galaxy showed that Coma P consists of two interacting dwarf galaxies, one of which has a weak star formation, and the second galaxy has a very low surface brightness, there is no star formation

Abstract—This paper presents the functional design of “Quantochron 5-48” high temporal resolution system for multidimensional chronometration of stochastic fluxes. The device can determine the photon arrival times by array detectors and the accompanying spatial, spectral, and polarization characteristics of these photons, with a sampling time of 10 nanoseconds and the accuracy of UTC calibration provided

AbstractWe calculate models of extended stellar atmospheres with a temperature in the range of 12 000–40 000 K and a mass loss rate of \({{10}^{{ - 6}}}\)–\({{10}^{{ - 4}}}{{M}_{ \odot }}\)\({{{\text{yr}}}^{{ - 1}}}\). A large number of objects with emission spectra, such as luminous blue variables, FeII—emission line stars, Of/late-WN stars, and even ultraluminous X-ray sources often have effective

Abstract—We report the results of laboratory tests of the first version of the high-resolution fiber-fed spectrograph designed for the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS). During laboratory tests a spectral resolution of about 70 000 was achieved. The peak efficiency of the entire optical path of the spectrograph (without light losses at the CCD, primary mirror

Abstract—We use the archival data obtained with the Hubble space telescope to measure distances by the tip of the red-giant branch (TRGB) method to SNIa parent galaxies. Our sample consists of four galaxies: NGC2841, NGC4496A, NGC4535, and NGC4527. For three of them, we were able to determine only the lower bounds of the distance. For the galaxy NGC4527, we estimated the TRGB distance modulus: (m − M)0

AbstractThe correlation between the data obtained with two gravitational wave (GW) detectors (in Rome and in Maryland) and two neutrino detectors (LSD in Italy and Kamiokande in Japan) has been studied in more detail. If we indicate with U1 the response of the gravitational wave detectors and with U2 the response of the neutrino detectors, we find that there is a clear time correlation between U1 and

Abstract—We present the Hα images of ultra-flat (UF) spiral galaxies seen practically edgeon. The galaxies have the angular diameter in the B band \(a > 1.9' \) and the apparent axial ratio (a/b) > 10. We found that their Hα images look, on average, almost two times thinner than those in the red continuum. The star-formation rate in the studied objects, determined from the Hα flux, is in good agreement

Abstract—We report the development of a photosensor device based on a position-sensitive detector with a gallium arsenide (GaAs) cathode and a 16-element anode. In the case of asymmetric heterostatic circuit (electrodes combined in fours) its working field was limited by 10 mm (for a 18-mm photocathode). Implementing a scheme of analog coding of the coordinates of the centroids of electron avalanches

Abstract—Using modern published data on velocities and spectroscopic definitions of chemical elements in stellar objects of the Galaxy, we investigated the relationship of chemical composition with the kinematics of different populations. The paper shows that the old stellar populations of the Galaxy, belonging (by the kinematic criterion) to the thick disk subsystem—globular clusters, field variables